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Math Help - what does e^x mean?

  1. #1
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    what does e^x mean?

    for something like this: 12e^x-20=0 how do i find x?
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    i guess i'm answering my own question but i'm assuming i take the ln of both sides so essentially it would be ln (40/12) which is 1.2039?
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    Quote Originally Posted by frozenflames View Post
    for something like this: 12e^x-20=0 how do i find x?
    Do you realize that you posted this question in the Pre-Calculus forum?
    Are you doing a course in Pre-Calculus?
    If so, surely you know what e^x means.
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  4. #4
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    Quote Originally Posted by frozenflames View Post
    i guess i'm answering my own question but i'm assuming i take the ln of both sides so essentially it would be ln (40/12) which is 1.2039?
    This is correct, but like Plato said your thread title is strange. e is just a number, so e^x is (e*e*e*e...), x times.
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  5. #5
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    Quote Originally Posted by frozenflames View Post
    for something like this: 12e^x-20=0 how do i find x?
    Quote Originally Posted by frozenflames View Post
    i guess i'm answering my own question but i'm assuming i take the ln of both sides so essentially it would be ln (40/12) which is 1.2039?
    If you post your working that led to this answer then your error can be explained (because this answer is wrong).
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    Quote Originally Posted by mr fantastic View Post
    If you post your working that led to this answer then your error can be explained (because this answer is wrong).
    Spoiler:
    12e^x-20=0

    12e^x=20 \Rightarrow e^x=\frac{20}{12}

    \ln(e^x)=\ln(\frac{20}{12}) \Rightarrow x\ln(e)= \ln(\frac{20}{12})


    I get the same answer as OP. What did I do wrong?
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  7. #7
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    Quote Originally Posted by Jameson View Post
    Spoiler:
    12e^x-20=0

    12e^x=20 \Rightarrow e^x=\frac{20}{12}

    \ln(e^x)=\ln(\frac{20}{12}) \Rightarrow x\ln(e)= \ln(\frac{20}{12})


    I get the same answer as OP. What did I do wrong?
    What you got (and which is correct) is
    Spoiler:
    x = \log_e \frac{20}{12}

    This is not the same as \log_e \frac{40}{12} (which is what the OP got) ....!
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  8. #8
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    Oh duh. I misread his answer. Silly me.
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